使用java生成字母验证码

import java.awt.BasicStroke;import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;public class VerifyCode {  //图片宽高  private int w=70;  private int h=35;  private Random r=new Random();  private String[] fontNames={"宋体","华文楷体","黑体","微软雅黑","楷体_GB2312"};  private String codes="234567890qwertyuipasdfghjkzxcvbnmQWERTYUIPASDFGHJKZXCVBNM";  private Color bgColor=new Color(255,255,255);  private String text;  //生成随机颜色  private Color randomColor(){    int red=r.nextInt(150);    int green=r.nextInt(150);    int blue=r.nextInt(150);    return new Color(red, green, blue);    }  //生成随机字体  private Font randomFont(){    int index=r.nextInt(fontNames.length);    String fontName=fontNames[index];    int style=r.nextInt(4);//0 无 1 粗体 2 斜体 3 粗+斜    int size=r.nextInt(5)+24; //生成随机字号 24~28    return new Font(fontName, style, size);  }  //干扰线  private void drowLine(BufferedImage image){    //生成4条干扰线    int num=4;    Graphics2D bi=(Graphics2D) image.getGraphics();    for (int i = 0; i < num; i++) {      int x1=r.nextInt(w);      int x2=r.nextInt(w);      int y1=r.nextInt(h);      int y2=r.nextInt(h);      bi.setStroke(new BasicStroke(1.5F));      bi.setColor(Color.BLUE);//干扰线色      bi.drawLine(x1,y1,x2,y2);    }  }  //随机生成一个字符  private char randomChar(){    int index=r.nextInt(codes.length());    return codes.charAt(index);  }  //图片缓冲区  private BufferedImage createImage(){    BufferedImage image=new BufferedImage(w, h, BufferedImage.TYPE_INT_BGR);    Graphics2D bi=(Graphics2D) image.getGraphics();    bi.setColor(this.bgColor);    bi.fillRect(0, 0, w, h);    return image;  }  //生成图片  public BufferedImage getImage(){    BufferedImage image=createImage();    Graphics2D bi=(Graphics2D) image.getGraphics();    StringBuilder sb=new StringBuilder();    for (int i = 0; i <4; i++) {      String string=randomChar()+"";      sb.append(string);      //每个字符占图片1/4宽      float x=i*1.0F*w/4;      //随机字体格式      bi.setFont(randomFont());      bi.setColor(randomColor());      //把字写在图片适当处（h-6指图片距底部6个高度）      bi.drawString(string, x, h-6);    }    this.text=sb.toString();    drowLine(image);    return image;  }  //返回得到的字体  public String getText(){    return text;  }  //把图片写入指定位置  public static void output(BufferedImage image,OutputStream out){    try {      ImageIO.write(image, "JPG", out);    } catch (IOException e) {      e.printStackTrace();    }  }}